Been meaning to write this up for a while now; I actually participated in Day9TV’s DK30 over the winter and completely re-vamped my safety gear on the Miata.
I wasn’t overly happy or thrilled with the fact that passing the broomstick test required a) drilling holes through the sides of my aftermarket seat (and therefore compromising the structural integrity, because I am an idiot), b) any amount of slouch, and c) certain seat brackets that weren’t exactly user-friendly AND clearly had room underneath to spare, which would theoretically eliminate b).
I also wasn’t happy with my 4-point harnesses (SCCA regulations on various events require 5+), and I’m ashamed to admit I had zip-tied them to be tighter on my body – not exactly the safest thing.
So I embarked on a quest to, with essentially a blank check, revamp all relevant gear.
Step 1: the seat, aka the easy part. I decided on a Sparco Sprint from Fab9Tuning - they’re local and I love throwing them my business when I can; they’ve always treated me well. It’s super comfy (way more padding than my previous Momo), and came with holes in the side pre-made!
I initially tried to use a PCI bracket, but I wasn’t happy with it for a number of reasons, and discovered that Jerfspeed offered a bracket that specifically targeted removing the “rear humps” in favor of getting even lower. Unfortunately, contacting the maker of the Jerfspeed bracket revealed that it’s not super compatible with Sparco Sprints; the Bell Raceworks and Track Dog Racing mounts are really the only remaining options. I went with the former, as they allow the adjustability I want long-term to support multiple drivers with varying seat positions.
Unfortunately, this started a rabbit hole: they require spacers, due to the trapezoidal shape of any given seat (but namely the Sprints) – and that forced me to dust off and fire up CAD to create some custom spacers, prototype them, and eventually fab them out of aluminum blocks. That’s a little better/safer than nylon!
This started a need for multiple iterations and designs; I think I’m on version 4 now, where version 1 was…not great. Note that all this was measured by hand, and there’s a lot of opprotunity for error; perhaps having the original Bell Raceworks CAD designs would have helped…
Step 2: The belts. I went with a 6-point 3” Schroth Profi. I’m under the distinct impression 2” belts are only good if you have a HANS device (maybe next year), and that 6-point is a lot friendlier to males than 5-point.
This had almost everything I wanted. Mounts to eyebolts that are installed under the seat (through the floor, in positions I measured out); eyebolts in the stock seatbelt locations*, and then does harness wraps around my roll-bar (no more zip ties!!!).
Except. The eyebolts directly collide against the Bell Raceworks seat brackets. Back to the ol’ drawing board. Or rather, cut out unneccesary material until morale improves. Now the Raceworks brackets have giant slices missing, but don’t collide…
I’d be a little more worried about structural integrity of said brackets if they weren’t cast out of single solid pieces of rather thick material. As far as safety compromises go, that one’s pretty minor.
Step 3: Repeat. I came across a slightly-used slightly-out-of-date Sparco Sprint; mounted that to a passenger-side PCI bracket (didn’t care about fitment there because I’m not gonna be a passenger very often), and came across a slightly-used slightly-out-of-date 3” Schroth Profi. That one was WAY easier to install and didn’t collide into the PCI bracket. Tada!